IMIDAZOLONE AND IMIDAZOLIDINONE ARTIFACTS OF A PIVOTAL IMIDAZOLTHIONE, ZYZZIN, FROM THE POECILOSCLERID SPONGE ZYZZA-MASSALIS FROM THE CORALSEA - THE FIRST THERMOCHROMIC SYSTEMS OF MARINE

Dry acetone extracts of the freeze-dried, deep-red powder of the poeci losclerid sponge Zyzza massalis (DENDY) from the Coral Sea gave the or ange alkaloid zyzzin ndol-3-yl)-1,5-dihydro-5-thioxo-1H-imidazol-1-one ; 14), which underwent exchange of the 5-thioxo for the 5-oxo group du ring aqueous chromatographic workup, giving yellow 13. Both 13 and 14 added hydroxyIic solvents at C(4)=N giving colourless, racemic product s, 3 and 8, respectively, by incorporation of MeOH and 10 and 11, resp ectively, by incorporation of H2O. On warming 3 or 10 in DMSO, 13 was recovered, thus furnishing a novel thermochromic system. Optically act ive (+)-12, which may be viewed to derive From enzymatic reduction of 14 at C(4)=N followed by S --> O exchange, was also isolated from this sponge, along with the linear amides 16 and 19. Compound 3 proved to have antibacterial and antifungal activities.